LSM330DLCTR datasheet(23/66 Pages) STMICROELECTRONICS

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LSM330DLC

Functionality

Doc ID 022162 Rev 2

23/66

4.4

FIFO

The LSM330DLC embeds 32 slots of 16-bit data FIFO for each of the three output channels:

yaw, pitch and roll. This allows consistent power saving for the system, since the host

processor does not need to continuously poll data from the sensor, but can wake up only

when needed and burst the significant data out from the FIFO. This buffer can work

accordingly in five different modes: Bypass mode, FIFO mode, Stream mode, Bypass-to-

Stream mode and Stream-to-FIFO mode. Each mode is selected by the FIFO_MODE bits in

the FIFO_CTRL_REG_G register. Programmable watermark level, FIFO_empty or

FIFO_Full events can be enabled to generate dedicated interrupts on the DRDY_G/INT2_G

pin (configured through the CTRL_REG3_G register and event detection information is

available in the FIFO_SRC_REG_G register. Watermark level can be configured to WTM4:0

in the FIFO_CTRL_REG_G register.

4.4.1

Bypass mode

In Bypass mode, the FIFO is not operational and for this reason it remains empty. As

described in Figure 6 below, for each channel only the first address is used. The remaining

FIFO slots are empty. When new data is available the old data is overwritten.

Figure 6.

Bypass mode

4.4.2

FIFO mode

In FIFO mode, data from the yaw, pitch and roll channels is stored in the FIFO. A watermark

interrupt can be enabled (I2_WMK bit in the CTRL_REG3_G register) in order to be raised

when the FIFO is filled to the level specified in the WTM 4:0 bits of the FIFO_CTRL_REG_G

roll). When full, the FIFO stops collecting data from the input channels. To restart data

collection, the FIFO_CTRL_REG_G register must be written back to Bypass mode.

FIFO mode is represented in Figure 7: FIFO mode.

x31

y31

z31

xi,yi,zi

empty

AM07231v1

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